I prefer the good old paper sheet of TANs, which at least DKB still uses. I had that exact pictured chipTAN reader; the display failed after about a year, and it was incredible hassle to get a new one activated with the Berliner Volksbank. It wasn't very good at reading the flashing barcode either, usually took a few tries.

It's a good idea, certainly, just a partly lousy implementation. Some banks will offer the option of sending you a TAN via SMS instead (so your phone is the "something you have"), but usually for a fee.